Hydrostatic re-tests are performed on gas cylinders and trailer tubes which are used to supply industrial gases. In this paper we review how to apply acoustic emission tests during periodic inspections to detect flaws, i.e., internal corrosion and cracks, which could occur on these containers during service. It appears that internal corrosion can be very easily detected at low pressure. However, to be sure of detecting cracks, it is best to perform AE tests during pressurization up to the test pressure. AE testing carried out during hydro-testing improves the reliability of the inspection, presents a greater accuracy in flaw detection than the water jacket test, and allows safe extension of the interval between re-tests.
